76 Maternal Inheritance aiid Mendelimn 



normals ; secondly that the normal and the grey segregate from each 

 other in their succeeding generation as other Mendelian characters do ; 

 thirdly that it is much easier to free the normal form from the 

 antagonistic character than the grey ; and, lastly, that the normal form 

 does not produce any other form when it becomes free from the grey 

 form, while the grey form segregates into another form even after being 

 freed from the normal form. From this fact we may safely infer that 

 the grey is more complicated in its constitution than the normal. 



Series 3. Grosses between Yellow and White forms of Japanese 

 Tetravoltine Breed, " Onodahime." (Fig. 9, a and b.) 



Normal Japanese tetravoltine breeds are generally white cocoon- 

 spinners, as far as we are aware. In the year 1905, we obtained a 

 mixed breed consisting of white and yellow cocoon-spinners, the latter 

 being a yellow-blooded form. Each form was reared separately and was 

 established as a constant form. In the spring of 1907 reciprocal 

 crossings between these forms were made. 



Yellow females mated with white males gave Fi eggs which are 

 all yellow when newly laid^ (Fig. 9, b). This is the characteristic egg- 

 colour of the yellow form. The reversed mating gave, on the contrary, 

 all pale white Fi eggs (Fig. 9, a) which is also the characteristic colour 

 of the white form. It will be necessary to note here that the colour of 

 newly laid eggs is determined by that of the shell and the yolk, both of 

 them being maternal in their origin. 



The worms which came out from the reciprocal Fi eggs were reared 

 in the late autumn of the same year. All the worms were yellow- 

 blooded and spun yellow cocoons without any exception. The moths 

 paired inter se gave all yellow F^ eggs which are quite the same as 

 those laid by the pure yellow forms. 



In the spring of 1908, the Fz yellow eggs gave two kinds of worms, 

 the one being yellow-blooded, the other white-blooded ; the total figures 

 found in those matings are shown below : — 



Number Number of yellow- 



of Group blooded worms 



I 485 



II 567 



Totals ~ Z. 1,052 



Mendelian expectation 1,035 



1 In this series of experiments, we only refer to the colour of the egg when newly laid, 

 i.e. the colour of eggs before the formation of the blastoderm takes place. 



